本研究主要探討AlxCoCrFeNi高熵合金（High-Entropy Alloys, HEAs）在不同鋁元素比例下之熱挫曲行為。研究透過考量材料參數的溫度相依性，分析環形盤在Clamped- Free、Free- Free與Free- Clamped的三種邊界條件的熱挫曲特徵值差異，並獨立分析各材料參數對挫曲特徵值之具體影響。
研究結果表明，邊界條件是決定熱挫曲模態與結構抗挫曲能力的主導因素。在「內環自由、外環固定（Free-Clamped）」條件下，結構呈現，展現最佳抗挫曲能力；反之，「完全無拘束（Free-Free）」條件則呈極易發生熱挫曲。在材料參數方面，熱膨脹係數的溫度相依性是造成熱挫曲特徵值下降的主因；然而，楊氏模數可提供部分正向補償作用以減緩穩定性衰退。值得注意的是，熱傳導率的影響則具備高度的邊界條件依賴特性，當外部邊界受拘束時，熱傳導率與熱膨脹係數會產生顯著的類疊加效應，導致特徵值隨溫度上升而下降。
在合金成分的探討中，則發現尤以鋁元素比例x=1.25之高熵合金展現出最佳的高溫穩定性。此優勢源於其熱膨脹係數隨溫度上升的增幅較小，因此在各類邊界條件下皆具備優異的抗挫曲表現。幾何部分，透過不同軸向厚度的比較證實，在薄板範疇內，特徵值與環形盤厚度呈平方正比關係。而最後，內環基礎溫度的提升則將降低外環的臨界挫曲溫度，不過x=1.25仍然在Free- Clamped與Clamped- Free展現較高的外徑臨界挫曲溫度。

This study investigates the thermal buckling behavior of High-Entropy Alloys (HEAs) with varying aluminum elemental ratios. By considering the temperature dependence of material properties, this research analyzes the differences in thermal buckling eigenvalues of annular discs under three boundary conditions—Clamped-Free, Free-Free, and Free-Clamped—and independently evaluates the specific impact of each material parameter on the buckling eigenvalues.
The results indicate that boundary conditions are the dominant factor dictating the thermal buckling modes and structural resistance to buckling. Under the Free-Clampedcondition, the structure exhibits a mode 3 buckling shape and yields the highest eigenvalue, demonstrating optimal buckling resistance. Conversely, the fully unrestrained Free-Free condition presents a mode 2 (potato-chip-like) buckling shape, rendering it highly susceptible to thermal buckling. Regarding material parameters, the temperature dependence of the coefficient of thermal expansion (CTE) is the primary cause of the degradation in thermal buckling eigenvalues. However, Young's modulus provides a partial positive compensation effect, mitigating the decline in structural stability. Notably, the influence of thermal conductivity exhibits a strong dependency on boundary conditions. When the outer boundary is constrained, the thermal conductivity and CTE produce a significant pseudo-superposition effect, leading to a drastic decrease in eigenvalues as the temperature rises.
In the evaluation of alloy compositions, the HEA with an aluminum ratio of x=1.25 exhibits optimal high-temperature stability. This advantage stems from the relatively small increment in its CTE with rising temperatures, thereby demonstrating excellent buckling resistance across all evaluated boundary conditions. Geometrically, comparisons of varying axial thicknesses confirm that within the thin-plate regime, the buckling eigenvalue is directly proportional to the square of the annular disc's thickness. Finally, an elevation in the base temperature of the inner ring lowers the critical buckling temperature of the outer ring. Nevertheless, the x=1.25 alloy maintains a higher outer critical buckling temperature under both Free-Clamped and Clamped-Free conditions.

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